This invention relates to footwear construction, and more particularly to an article of footwear formed with an upper, where the upper can expand to accommodate various sizes.
In footwear construction, there is generally provided a sole with an upper formed thereon. There can also be included a heel, as well as other portions, depending upon the type and shape of the shoe.
However, since the shoe is formed of stiff material, typically leather, plastic, canvas, or the like, and since the upper is connected to the sole by means of stitching, adhesive, or the like, the size of the shoe is generally fixed to a particular foot size.
As a result, when one purchases a shoe, boot, slipper or the like, the size of the footwear must be commensurate with the foot size. If the size is too big or too small, it will not fit properly and will provide discomfort, and frequently damage to the wearer's foot.
As a result, it is necessary to carry a complete selection of footwear to accommodate all of the various foot sizes. Such sizes must not only include variations in length, but also variations in width, as well as combinations of length and width sizes. This requires a considerable amount of stock in any particular style in order to accommodate all foot sizes.
As a result, frequently, many sizes are not stocked in particular styles and the wearer must either resort to a different shoe style or compromise the particular foot size to one that is not exactly commensurate with his needs.
In addition to variations in size corresponding to different foot lengths and widths, even with a particular foot there are frequently variations during the course of the day as well as with changes in the seasons. For example, in the mornings when the foot is first placed in the shoe, after the foot has been raised for a considerable length of time during the nighttime in a rest position, the size of the foot is slightly smaller than at the end of the day when the foot has been in a vertical position with pressure on the foot for a considerable length of time. Similarly, during the summer, as a result of expansion, heat, moisture, and other conditions, the foot swells a bit in size greater than its winter size.
Despite these variations in foot size, during each day, each season, etc., a wearer generally does not change the shoe or other footwear between morning and nighttime to accommodate such changes, nor does he change the shoe size between summer and winter shoes. Accordingly, a shoe size that fits for certain days or certain times of the year may be discomforting for other periods of time.
Yet, furthermore, the comfort of the foot in the shoe will vary depending upon the thickness of the sock, stocking, etc., as well as because of various other factors concerning the effect of the environment on the shoe, the effect of the connection between the sole and the upper and many other variations.
Accordingly, with present existing footwear, even when a shoe is selected to fit a particular foot size, the shoe will not always provide a perfect fit and will not always give good comfort because of such variations during normal routines.
Another problem with existing footwear concerns the particular shape of the foot. While shoes are generally designed for an average foot shape, it is well known that such shape actually varies from person to person. While a particular style may accommodate one wearer's foot shape it may be most uncomfortable to another wearer even with the same foot size, since the particular shape of the foot may differ. This problem is even further compounded as a result of deformities in the foot, such as corns, bunions, etc.
As a result, existing footwear are not often designed to accommodate particular foot sizes and shapes, and in most cases a wearer must compromise style, size, shape, or some other aspect of footwear in order to obtain a shoe to wear.
In the prior art, an attempt has been made to try and accommodate at least a part of these problems by providing expandable shoes to accommodate a change in a single size. For example, U.S. Pat. No. 3,389,481 has a steel plate formed in the sole which permits movement between a first and second shoe size position. At the same time, the upper material itself is of crinkled leather, or the like, whereby it can be expanded between the two positions corresponding to the two sizes. Accordingly, especially for a child, the shoe can be utilized not only for the size for which it was purchased, but for the next size as well.
Another attempt to accommodate expansion of a shoe is provided in U.S. Pat. No. 1,110,624. In this case, there is provided an expandable edge portion in order to permit entry and exit of the foot into the shoe. The expansion is provided by means of an expandable rubber strap which is covered by a folded over piece of slitted leather to permit expansion of the rubber therebeneath. The leather is stitched at its bottom portion to prevent expansion of the leather itself and to only permit the leather to accommodate expansion of the rubber.
Neither of these approaches have truly addressed the essence of the problem of permitting full expansion of the entire upper in order to accommodate completely different foot sizes and shapes.